From the L.A. Times:

The Orange County Crime Lab produced inaccurate blood alcohol test results in 2,200 driving-under-the-influence cases filed by prosecutors this year — mistakes that could affect outcomes in dozens of cases.

Prosecutors in recent days sent letters to people charged with driving under the influence, including 900 whose cases resulted in convictions. The letters advised them that their cases were among those with miscalculations.

Crime lab officials said the “human error” occurred over nearly five months and led to mistakes in the forensic examination of blood alcohol content. But they insist the miscalculations were so few that they affect only about 200 cases.  As few as 20 people could see their blood alcohol test levels drop below 0.08%, California’s legal definition of DUI impairment.

But veteran DUI attorneys across Orange County said flaws with the lab’s basic testing probably will affect many more cases because sentence enhancements and negotiations are often based on how far over the legal limit a motorist was determined to be.

. . .

Orange County Crime Lab Director Bruce Houlihan said the facility, which serves the entire county, discovered flaws in its analysis Oct. 10 while conducting an audit.

“It was a human error that led to an instrument to be wrongly calibrated,” he said.